In chemical or petrochemical plants etc., it is common for fluid materials (e.g. liquids, gases etc.) to be conveyed from one location to another using equipment such as conduits or pipes (collectively referred to herein as “pipes”). Such pipes are often manufactured from metal sections that are joined together by welds. For example, when joining adjacent ends of pipe together, it is common for each end to be provided with a flange that is welded to the respective pipe end. Once each flange is thus secured to the pipes, they are then bolted together to form a sealed joint. Typically, a gasket or other such sealing means is provided between the opposed faces of the flanges. Such flanges may also be provided on nozzles secured, by welding, to holding tanks and other such vessels so that pipes can be connected thereto. Alternatively, the connections between lengths of pipe or other equipment may be welded directly together (i.e. butt welded) to form the seal. In either case, it will be appreciated that each welded joint or section must have integrity and form a complete seal so as to prevent leakage of the materials being transported. This is particularly important when handling potentially hazardous materials such as flammable or toxic liquids where leakage of such fluids can lead to catastrophic consequences. Therefore, for reasons of safety, it is often necessary to periodically test the integrity of the welds used in joining the various pieces of equipment (such as pipes, vessels, flanges and the like) together.
The prior art provides various tools for conducting weld integrity tests on conduits. Many of such known tools are used in pressure tests wherein a highly pressurized zone is created at least at the region of a weld being tested and such pressure monitored. In such tests, a drop in pressure signifies a failed weld. For example, U.S. Pat. Nos. 6,131,441 and 5,844,127 (the entire disclosures of which are incorporated herein by reference) teach weld testing tools that isolate a particular section of a pipe (such section including a weld) and subject the section to a high pressure fluid within a constrained annular space defined by the tool and the inner surface of the pipe. The pressure of the fluid within the annular space is monitored whereby a drop in such pressure signifies a leak in the weld.
U.S. Pat. Nos. 6,463,791 and 7,874,217 (the entire disclosures of which are incorporated herein by reference) also teach apparatuses for testing welds.
In some cases, it is necessary to seal an end of a pipe to conduct the above mentioned pressure test. In this regard, PCT Application number PCT/CA2011/050121 (the entire disclosure of which is incorporated herein by reference) provides a tool for sealing an end of a pipe that incorporates a gripper or clamp for engaging the exterior surface of the pipe. Similarly, PCT Application number PCT/CA2011/050122 (the entire disclosure of which is incorporated herein by reference) also provides a sealing tool for sealing an end of a pipe, which comprises a device that includes a gripping device for engaging both the interior and exterior portions of the pipe. The end sealing devices taught in these references may be used to seal one or both ends of a given pipe (or another opening such as the case with a pipe having a “T” junction). Once the device of PCT/CA2011/050121 or PCT/CA2011/050122 is secured to the one or more ends of the pipe, the interior of the pipe is then pressurized and the pressure monitored as indicated above. While the device taught in PCT/CA2011/050122 provides an efficient and effective sealing device for the ends of pipes, it may be difficult to handle when scaled for large diameter pipes (i.e. pipes greater than 24 inches or 36 inches in diameter) in view of its increased weight.
There exists a need for a device for sealing an end of a pipe, particularly large diameter pipes, and for conducting the type of weld integrity stress tests mentioned above. In particular, there is a need for an apparatus that can be easily mounted on an open end of a pipe so as to effectively seal the pipe opening and maintain such seal during pressurization of the pipe interior. Such pressurization may be associated with pipe integrity testing methods. Preferably, such apparatus would not subject the pipe to any significant damage.